The invention concerns a method for production of a lined gasket or a gasket insert for opposing wall surfaces of an enameled glass lined vessel.
It is well-known and frequently the case in the sealing of opposing wall surfaces of metal vessels having enameled or glass lined wall surfaces, such as connecting flanges, that the latter will deviate in surface characteristics due, for example, to the high burn-in temperatures of the steel wall which will warp. In particular, opposing, flanges of lined wall surfaces, to which agitator nozzles are mounted, often are not level. Inasmuch as a slip ring unit, or stuffing box, must be vertically positioned on the vessel, surface differences at the points of connection of the agitator nozzles are equalized or leveled by compensating inserts or gaskets. These equalizing gaskets are also useful in compensating for relatively large burn-in warpages which may occur in these vessels where manhole covers or reactor flanges, with very large diameters, are employed.
A method, proven for decades, for production of lined gaskets for enameled apparatus consists in segment-shaped compensating inserts being placed in the gaskets. These preferably consist of two IT-gaskets, as are well known to those with skill in the field, between which a corrugated ring, usually of a metal, is arranged, the IT-gaskets being surrounded by a shell of polytetrafluoroethylene. Segment-shaped equalizing inserts are fitted by grinding or filing the ends and surfaces, to take up the space between one IT-gasket and the corrugated ring. In instances where the gap caused by the burn warpages is relatively large between the sealing surfaces, several equalizing inserts must be arranged, one over the other in stacked arrangement until the gap is closed. The equalizing inserts usually consist of asbestos-containing materials which are cemented to the corresponding points of the adjacent IT-ring.
In these known methods of the type mentioned, the fitting of the gaskets between warped mounting flanges of the vessel wall and nozzle requires a relatively large expenditure of time; at times several hours are expended in the fitting of the lined gasket between the flange surfaces. In addition, skilled experienced and diligent laborers are necessary since a high degree of accuracy is required. In addition, grinding operations on asbestos-containing materials are injurious to health when the required safety regulations are not carefully maintained. An additional difficulty exists in operation in the fact that the lined gasket settles between the flanges at different rates which are dependent on the thickness of the lining causing leakage over time. Even with very careful original fitting during the fabrication, leakage may occur despite lengthy production operations thereby requiring new fittings. Further, experienced laborers are not always readily available resulting in considerable down-time of the operating apparatus and time-consuming and costly delays in manufacturing procedures.
It is therefore the object of the present invention to provide an improved method of sealing, from that known type previously mentioned, avoiding the many disadvantages and difficulties mentioned in a manner that the fitting operations for the sealing insert can be performed simply and quickly. A further object is to provide a novel resilient lining material for such a gasket insert.
The present invention comprehends the use of a hardening pasty substance which can be applied with relatively low expenditure of energy, for example with a spray gun, a spatula or other familiar application techniques, so that, in contrast to well-known methods, no grinding operations on asbestos-containing materials need be performed. Inasmuch as this method is relatively simple to perform, a fitting can also take place at the point of use without requiring highly skilled labor. The pasty substance should be composed of such materials that the hardened substance has suitable physical properties for the pertinent applicability, especially with regard to settling behavior, spring-back resilience and temperature resistance. A preferred pasty substance of this type has been found to be one that contains a filler of quartz powder whose void fraction is filled by a 2-components artificial resin. Depending on the application, other hardening materials are also usable, and which need not necessarily contain a filler, for example 1- or 2-components plastics or organic cement substances. The addition of a filler, however, enables an adaptation to the required properties during the processing and during operations, for example with regard to viscosity, elasticity, compressive strength, tensile strength, temperature resistance, heat expansion coefficient and pot time. Inorganic materials such as glass, quartz, aluminum oxide or graphite are primarily suited as fillers, which can be added in powder form with suitable granulation, or in fiber form.